(1) Field of the Invention
The present invention relates to a mobile track working machine, particularly a track leveling, lining and tamping machine useful for work in switch sections, comprising a machine frame mounted for mobility in an operating direction on a track including two rails fastened to ties defining cribs therebetween, each rail having a rail head, a field side and a gage side, and an apparatus for lifting and laterally moving the track in a switch section. The lifting apparatus comprises a vertically and laterally movable tool carrier frame, power-actuated drives linking the tool carrier frame to the machine frame for vertically and laterally moving the tool carrier frame with respect to the machine frame, and a pair of flanged wheels supporting the tool carrier frame for mobility on the track, a respective one of the flanged wheels being associated with each track rail and serving as track lining element. A respective rail gripping device is mounted on the tool carrier frame for engagement with the field side of the associated rail, the rail gripping device including a first rail gripping hook transversely and vertically adjustable for engagement with the associated rail and a rail gripping member of a different type for grippingly subtending the rail head at the field side of the associated rail.
(2) Description of the Prior Art
U.S. Pat. No. 4,627,360 dated Dec. 9, 1986, discloses a mobile track leveling, lining and tamping machine with tamping tool assemblies and a track lifting and lining unit equipped with tools operable in switch sections of railroad track. The tamping tool assemblies are transversely displaceable and have two or four independently driven tamping tools at the field and gage sides of each rail, each tamping tool being not only reciprocable in the direction of the track but also pivotal in a direction transverse thereto. This enables even very difficult switch sections to be tamped at least with one tamping tool while other tamping tools, which would encounter an obstacle upon immersion in the ballast, are pivoted out of the way. To enable complex and heavy switch sections with their very long ties, and whose rails are difficult to grip, to be leveled and lined, the track lifting and lining unit is longitudinally displaceably supported by two pairs of flanged wheels on the track and has a powerful rail gripping hook associated with each rail, each rail gripping hook being laterally and vertically adjustable by hydraulic cylinder drives. This arrangement enables each rail to be gripped either at the rail head or at the bottom. Such machines are of great importance in track rehabilitation work because the proper leveling and lining of switch sections is of particular value in view of their high construction costs. Suitable leveling and lining systems are used for the control of the lifting and lining tools. However, the accuracy of the track movement, particularly when the track is lifted for leveling, is somewhat impaired because of the weight of the switch section extending to the right or left of the main track and connected thereto by the long ties common to the main track and the track branching off at the switch. Therefore, it is often necessary in the operation of this machine to control the work at the branch track section again by means of the reference system, particularly during track leveling, and then to fix this track section at the accurate level by tamping the ties.
U.S. Pat. No. 4,457,234, dated July 3, 1984, also discloses a track leveling, lining and tamping machine with a track lifting and lining unit which comprises a tool carrier frame linked to the machine frame by a central pole at one end and supported on the track at its opposite end by a pair of flanged wheels. Laterally pivotal rail lifting rollers respectively precede and trail each flanged wheels for engagement with each rail. Two lifting drives and a common lining drive connect the tool carrier frame to the machine frame. The four lifting rollers are transversely aligned in pairs and engage the field sides of the rails. The lifting rollers may be replaced by rotatable mushroom-shaped members for subtending the rail heads or by rail gripping hooks capable of gripping either the rail head or the foot or bottom of the rail. Such a relatively simply constructed machine may be used successfully for work in an initial portion of a track switch but it cannot be operated in the area close to the frog because, as will be explained hereinafter, this requires special rail gripping arrangements.
A mobile track working machine of a similar type and operable in tangent track as well as in switch sections is disclosed in U.S. Pat. No. 4,323,013, dated Apr. 6, 1982. In this machine, two lifting and two lining drives connect the tool carrier frame of the rail lifting and lining unit to the machine frame. Pairs of independently laterally pivotal lifting rollers precede and trail each flanged wheel supporting the tool carrier frame on the associated rail for subtending the rail head at the field and gage side thereof. In addition, a vertically and laterally adjustable rail gripping hook is associated with each rail between the pairs of rail gripping rollers. The combination of the vise-like pairs of pivotal rollers and the hooks gripping each rail, it is possible to work even on the heaviest track switch sections. In one of the embodiments disclosed in this patent, only one gripping roller and one gripping hook is used for each rail for engaging the field side of the rail, the rail gripping hooks being vertically and laterally adjustable. The associated flanged wheel serves as lining element and cooperates selectively with the gripping roller and/or hook, depending on operating conditions, to provide a vise-like grip on the rail, thus serving as a satisfactory track gripping arrangement for most track leveling and lining operations, even in switches. This machine, too, has a leveling and lining reference system. It has been successfully used in commercial operations but has the same disadvantages outlined hereinabove, i.e. the weight of the switch section adjacent the main track subjects the lifting and lining tools as well as their drives to excessive strains, which unfavorably affects the accuracy of the desired track position. In an effort to alleviate such strains on the tools, it has been proposed to use lifting winches for the branch track section in cases of particularly heavy track switches but this requires additional operating personnel and also considerably slows down the work. The winches must be dismantled and erected again intermittently as the machine proceeds from tamping stage to tamping stage, which is time-consuming and uneconomical.
U.S. Pat. No. 4,342,263, dated Aug. 3, 1982, discloses a track leveling, lining and tamping machine whose track lifting and lining unit has a two-part tool carrier frame with a central pole attaching the unit to the machine frame. The lower carrier frame part has a pair of flanged wheels at a rear end and the central pole projects from a front end thereof and is longitudinally displaceably connected to the machine frame. The upper carrier frame part is centrally linked to the lower part and is equipped with a transversely displaceable or pivotal lifting hook associated with each rail adjacent the flanged wheel. For vertical adjustment of the lifting hook, the upper part may be raised by an adjustment drive with respect to the lower part. The unit has two lifting and lining drives and a longitudinal displacement drive enables the unit to be displaced in the direction of the track with resect to the machine frame. Since the unit has only a single rail gripping member for each rail, heavy track sections cannot be handled with this machine. This machine is obviously even more seriously beset by all the disadvantages outlined hereinabove when subjected to the heavy weight of a branch track section adjacent a main track in a track switch.
A track leveling, lining and tamping machine with an even simpler track lifting and lining unit is disclosed in British Patent No. 2,140,061, published Nov. 21, 1984. This unit has one pair of flanged wheels serving as lining elements and a vertically and laterally adjustable rail gripping member, such as a hook or roller, may be selectively engaged with the field side of each rail for cooperation with the associated flanged wheel. The machine has all the disadvantages outlined hereinabove when it comes to handling difficult and/or heavy track switches.